The present invention relates to room temperature curable epoxy novolac resin coating compositions containing hydrolyzed epoxy groups.
Walker in U.S. Pat. Nos. 3,632,836 and 3,787,508 discloses the use of hydrolyzed epoxy resins in epoxy resin coatings up to an amount of 20 percent by weight to improve the reactivity of the epoxy resin and to improve pigment dispersability in the epoxy resin coating composition.
Irwin in U.S. Pat. Nos. 3,891,525 and 3,991,028 discloses the use of hydrolyzed epoxy resins in water dispersed electrodepositable coating compositions employing an interpolymer of a hydroxyalkyl ester of an unsaturated acid and an amine-aldehyde resin.
Irwin et al in U.S. Pat. No. 4,145,234 disclose coating formulations of (1) an oil in water emulsion of a solution of a hydrolyzed diglycidyl ether of a bisphenol, a nonionic surfactant and a curing agent; or (2) a solution of a hydrolyzed diglycidyl ether of a bisphenol and a curing agent in alkoxyethanol or a mixture of alkoxyethanol with alcohols, ketones, carbitols or their acetates and, optionally, liquid aromatic hydrocarbon solvents. Such solution coating compositions are stated to have solid (non-volatile) content of from 15 to about 35 weight percent.
It has now been discovered that one or more of the properties of room temperature coatings prepared from epoxy novolac resins can be improved by hydrolyzing at least a portion of the epoxy groups of said novolac resin.